1. Field of the Invention
The present invention relates to a gas generator used in a restraining device installed in a vehicle, such as an air bag system, or the like, and more particularly to a gas generator used in a lateral collision air bag system for deploying an air bag on the side of an occupant.
2. Description of the Related Art
A gas generator of a side air bag for protecting an occupant during a lateral collision is often formed in an elongated shape due to attachment location restrictions.
US-A No. 2008/0078486 discloses a filterless-gas generator in which an initiator 32 is accommodated in one end portion of an elongated outer housing 12 and a diffuser portion formed with a gas discharge port 20 is provided in an opposite end portion.
In this gas generator, a booster cup 23 storing a booster agent and a divider 28 are disposed in the vicinity of the initiator 32, and an opening 28a is formed in the divider 28. A gas generating agent 16 is disposed in a space formed by an inner housing 14.
A booster 24 burned by the initiator 32 generates combustion products that enter the interior of the inner housing 14 through the opening 28a and burn the gas generating agent 16. Gas generated from the gas generating agent 16 passes through an orifice 18 in the inner housing 14 and escapes through a tubular gap between the outer housing 12 and the inner housing 14 to be discharged from gas discharge port 20 in the diffuser portion.
However, when this gas generator is activated, the gas generating agent 16 on the booster 24 side burns first, and therefore the generated gas passes through the unburned gas generating agent 16 to flow to the orifice 18, making it more difficult for the gas to flow. As a result, pressure in the interior of the inner housing 14 rises, and this pressure increase may cause constitutional members of the gas generator to break. Moreover, the gas generating agent 16 as a whole cannot be burned easily.
JP-A No. 2007-131254 discloses a gas generator such as that shown in FIG. 1, in which a tubular partition wall 19 (see FIG. 3) forming a combustion chamber 6 is disposed in the interior of a housing 3 that is short in an axial direction. Opening portions 22a, 22b are formed in a peripheral wall surface 19a of the tubular partition wall 19, and these opening portions 22a, 22b are formed by projecting a part of the peripheral wall surface 19a outwardly such that the opening portion 22a is oriented toward one end portion of the tubular partition wall 19 and the opening portion 22b is oriented toward an opposite end portion.
A gas generating agent 9 for inflating an air bag is disposed in the interior of the tubular partition wall 19, and combustion gas generated by the gas generating agent 9 is discharged to the outside through the opening portions 22a, 22b to flow toward the respective end portions of the tubular partition wall.
In the gas generator according to JP-A No. 2007-131254, when the combustion gas flows from the inside of the tubular partition wall toward the outside, basically the entire amount of the combustion gas (gas for inflating an air bag) passes through the opening portions 22a, 22b. Further, the gas generator according to JP-A No. 2007-131254 improves the efficiency in purifying and cooling the combustion gas, and is not concerned with improving an ignition/combustion performance of the gas generating agent.